The instant invention concerns the field of chondrocyte transplantation, bone and cartilage grafting, healing, joint repair and the prevention of arthritic pathologies. In particular methods for the preparation of the graft site, instruments for such preparation and for the autologous transplantation of cells to the prepared graft site.
More than 500,000 arthroplastic procedures and total joint replacements are performed each year in the U.S. Approximately the same number of similar procedures are performed in Europe. Included in these numbers are about 90,000 total-knee replacements and around 50,000 procedures to repair defects in the knee per year in Europe. The number of procedures are essentially the same in the U.S. (In: Praemer A., Furner S., Rice, D. P., Musculoskeletal conditions in the United States, American Academy of Orthopaedic Surgeons, Park Ridge, Ill., 1992, 125). A method for regeneration-treatment of cartilage would be most useful, and could be performed at an earlier stage of joint damage, thus reducing the number of patients needing artificial joint replacement surgery. With such preventative methods of treatment, the number of patients developing osteoarthritis would also decrease.
Techniques used for resurfacing the cartilage structure in joints have mainly attempted to induce the repair of cartilage using subchondral drilling, abrasion and other methods whereby there is excision of diseased cartilage and subchondral bone, leaving vascularized cancellous bone exposed (Insall, J., Clin. Orthop. 1974,101,61; Ficat R. P. et al, Clin Orthop. 1979, 144, 74; Johnson L. L., In: Operative Arthroscopy, McGinty J. B., Ed., Raven Press, N.Y., 1991, 341).
Coon and Cahn (Science 1966, 153, 1116) described a technique for the cultivation of cartilage synthesizing cells from chick embryo somites. Later Cahn and Lasher (PNAS USA 1967, 58, 1131) used the system for analysis of the involvement of DNA synthesis as a prerequisite for cartilage differentiation. Chondrocytes respond to both EFG and FGF by growth (Gospodarowicz and Mescher, J. Cell Physiology 1977, 93, 117), but ultimately lose their differentiated function (Benya et al., Cell 1978, 15, 1313). Methods for growing chondrocytes were described and are principally being used with minor adjustments by Brittberg, M. et al. (New Engl. J. Med. 1994, 331, 889). Cells grown using these methods were used as autologous transplants into knee joints of patients. Additionally, Kolettas et al. (J. Cell Science 1995, 108, 1991) examined the expression of cartilage-specific molecules such as collagens and proteoglycans under prolonged cell culturing. They found that despite morphological changes during culturing in monolayer cultures (Aulthouse, A. et al., In Vitro Cell Dev. Biol., 1989,25,659; Archer, C. et al., J. Cell Sci. 1990,97,361; Hanselmann, H. et al., J. Cell Sci. 1994,107,17; Bonaventure, J. et al., Exp. Cell Res. 1994,212,97), when compared to suspension cultures grown over agarose gels, alginate beads or as spinner cultures (retaining a round cell morphology) tested by various scientists did not change the chondrocytexe2x80x94expressed markers such as types II and IX collagens and the large aggregating proteoglycans, aggrecan, versican and link protein did not change (Kolettas, E. et al., J. Cell Science 1995,108,1991).
The articular chondrocytes are specialized mesenchymal derived cells found exclusively in cartilage. Cartilage is an avascular tissue whose physical properties depend on the extracellular matrix produced by the chondrocytes. During endochondral ossification chondrocytes undergo a maturation leading to cellular hypertrophy, characterized by the onset of expression of type X collagen (Upholt, W. B. and Olsen, R. R., In: Cartilage Molecular Aspects (Hall, B and Newman, S, Eds.) CRC Boca Raton 1991, 43; Reichenberger, E. et al., Dev. Biol. 1991, 148, 562; Kirsch, T. et al., Differentiation, 1992, 52, 89; Stephens, M. et al., J. Cell Sci. 1993, 103, 1111).
Excessive degradation of type II collagen in the outer layers or articular surfaces of joints is also caused by osteoarthritis. The collagen network is accordingly weakened and subsequently develops fibrillation whereby matrix substances such as proteoglycans are lost and eventually displaced entirely. Such fibrillation of weakened osteoarthritic cartilage can reach down to the calcified cartilage and into the subchondral bone (Kempson, G. E. et al., Biochim. Biophys. Acta 1976, 428, 741; Roth, V. and Mow, V. C., J. Bone Joint Surgery, 1980, 62A, 1102; Woo, S. L.-Y. et al., in Handbook of Bioengineering (R. Skalak and S. Chien eds.), McGraw-Hill, N.Y., 1987, pp. 4.1-4.44).
Descriptions of the basic development, histological and microscopic anatomy of bone, cartilage and other such connective tissues can be found for example in Wheater, Burkitt and Daniels, Functional Histology, 2nd Edition, (Churchill Livingstone, London, 1987, Chp. 4). Descriptions of the basic histological anatomy of defects in bone, cartilage and other connective tissue can be found for example in Wheater, Burkitt, Stevens and Lowe, Basic Histopathology (Churchill Livingstone, London, 1985, Chp. 21).
Despite the advances in cultivating chondrocytes, and manipulating bone and cartilage, there has not been great success with the attempts to transplant cartilage or chondrocytes for the repair of damaged articulating surfaces. The teachings of the instant invention provide for effective, and efficient means of promoting the transplantation of cartilage and/or chondrocytes into a defect in an articulating joint or other cartilage covered bone surface, whereby cartilage is regenerated to fix the defect. The instant invention also provides for surgical instruments which are designed prepare the graft site so as to facilitate the efficient integration of grafted material to the graft site.
The instant invention provides a method for the effective treatment of articulating joint surface cartilage by the transplantation of chondrocytes in a suitable matrix, to a surface to be treated, with a hemostatic barrier and a cell-free covering-patch comprising; first placing a hemostatic barrier proximal to the surface to be treated, placing chondrocytes in a suitable matrix upon the surface to be treated distal to the hemostatic barrier, covering the surface to be treated with a cell-free covering-patch. A hemostatic barrier, as will be further described below, is a barrier which inhibits the penetration of vascularizing cells and tissue into the grafted material. In particular, the instant method provides for a hemostatic barrier that is a resorbable, semi-permeable material which inhibits or prohibits vascular infiltration through the barrier. In one embodiment the hemostatic barrier contains collagen. Cell-free, is used herein as in the art, and means a material that is substantially free from intact cells which are capable of further cell division, promulgation or biological activty. In a preferred embodiment, a cell-free material is free from all intact nucleated cells. In one embodiment, the instant method encompasses the use of a cell-free covering patch which contains a semi-permeable collagen matrix. In one preferred embodiment of the method, the porous surface of the cell-free covering-patch is directed towards the implant material.
The instant invention further provides for the autologous transplantation of collagen or chondrocytes to a graft site, wherein the graft site has first been prepared by surgical manipulation to better accept the grafted material. In one embodiment, the graft site is sculpted such that the walls of the graft site are contoured in an undulating pattern such that the grafted material, when placed within the graft site and expanded to contact the graft site wall, there will be resistance against removal or expulsion of the entire graft from the graft site. The instant invention further provides for surgical instruments designed to sculpt the graft site as taught by the method of the invention.
The invention further provides for a kit for cartilage and/or chondrocyte transplantation onto the surface of an articular joint wherein said kit comprises a hemostatic barrier, cell-free semi-permeable covering-patch, and organic glue. In a further embodiment, the kit can optionally further provide one or more surgical instruments which can be used to sculpt the graft site in accordance with the methods of the instant invention.